Method of and apparatus for pressure concrete molding



June 30, v Wl M. MEACHAM 1,811,950

METHOD OP ANDAPPARATUS FOR PRESSURE CONCRETE MOLDING Filed Aug. 1l. 1928 3 Sheets-Sheet 1 u, &V/////// June 3o, 1931. Y

METHOD w. M. MEACHAM 1,811,950

OF' AND APPARATUS FOR PRESSURE CONCRETE MOLDING 3 sheets-Sheet 2 Filed Aug. l1, 1928 June 30, 1931. w M, MEACHAM 1,811,950

METHOD OF AND APPARATUS FOR PRESSURE CONCRETE MOLDING Filed Aug. ll, 1928 3 Sheets-Sheet 3 HHHII nwnto'o Patented `lune 1931 'i UNITED srArEs WILLIAM M. MEACHAM, or SEATTLE, wAsrrnireiTorr'y y HETHODOF AND APPARATUS FOR PRESSURE CONCRETE HOLDING Application led August 11, 1928. lSerial No. 298,944.

My invention relates to the casting of concrete by the use of molds and the elimination of surplus water therefrom by the application of pressure thereto. It consists of a methodv of carrying this out and of an apparatus for use in carrying out the method.

The object of my invention is to improve the methods of pressure casting .of concrete, and to provide an apparatus operable by a method wherein it is not necessary to give the molds unusual strength to thereby resist the high pressures employed, and tomake certain that a minimum desired compression of the concrete has been produced throughout its entire mass.

As the strength of concrete is not substantially increased b being subjected to pressure for longer t an twenty minutes, it is desired that a pressure process be such as can be applied to simple molds which can be set aside for the time required for the concrete to set and the pressure equipment used on other molds. Such a process is here described.

In the accompanying drawings I have shown an apparatus which may be eiectively used to carry out my method.

Figure 1 is a central vertical section of a typical apparatus which has been chosen as suitable for illustrating my invention.

Figure 2 is an upper end view with th head broken away at one side.

Figure 3 is a transverse section taken on the plane of the broken line 3-3 of Figure 1.

Flgure 4 `is a section on the line 4 4 ofl Figure 1. i

Figure 5 is a longitudinal section of a short portion of the water collectingl and drainage pipe.

Figure 6. shows by a detail in sectional 40 plan view on line 6-6 of Figure 1, the manner whereby pressure may be applied to central or intermediate portions of the objects bering cast. l

Figure 7 illustrates the use of a different type of mold, which may be made of a relait. In consequence, it need not be of any tively weak material, and yetv permit the` api plication of heavy pressures to the concrete.

Figure 8 isa mold ofthe same type as that of Figure 7, except that vthe use cfa mold of elastic or iiexible material is contemplated, whereby undercut articles may be made.4

It is a well-recognized fact that concrete to' which sufficient pressure has been applied to expel the surplus water while' yet in a plastic state, is stronger and more dense than concrete from which'the surplus water has not been removed. lThe application of pressure toconcrete, as it has usually been practised, has involved the use o; strong and expensive molds, capable of resisting these pressures, which has increased-the cost ofthe product. Itis one aim of my Linvention to make it possible to use molds of a cheaper type of construction, thereby decreasing the cost of the product. 1

The central feature, whereinmy present invention differs from former methods, is that the strains produced by the pressure employed are not resisted bythe mold itself, but by a container or pressure chamber into which the mold is placed, the mold itself being ex-v teriorly subjected to substantially the same pressure as is applied to the concrete within greater strength than would be needed when molding under atmospheric pressure.

While I shall herein use the term concrete, as descriptive of the material employed, it isv intended that'this be 'ven a generic meaning and scope which will include any material whichl is mixed in a plastic state and which setsf or hardens .by the lapse of time. Gypsum products are a good example of such other materials; 1

For the' purposes of illustrating my invention, I have shown in Figures 1 to 6 inclusive, an apparatus designed for castin a post with a central channel or duct, such, or instance, as would well serve as a lamp post. Any 00 object capable of being cast in a mold may be made by my process.

For casting such an object, a two-part mold may be used. A higher division of the mold been provided at the inner edge of the flange 10, a narrow marginal flange 12, which flanges of the two halves form the `contacting surfaces between the two halves. There is thus `formed an exteriorly opening crack or trough for the reception of a packing gasket 13.

Placed preferably as nearly `as is feasible -at the central axis of the body being cast, is

a water and air collecting and discharging pipe, which is of composite construction. An approved construction is as follows:n An' outer pipe 3 has a great many small holes 30- in its wall, distributed throughout substantiallv its entire length. They have been 'omitted for short distances at its ends.

Within the. pi e 3, but -enough smaller to leave a considerable space between them,- is a small pipe 31, which also has its sides perforated, as by holes 32. Wrapped about the inner pipe 31 is a layer of filtering or screeninglmaterial 33, such as wire or fabric cloth, an between the inner pipe 31 and pipe 3 is a layer of packed sand or other granular .material, throughv which water will ass. The composite pipe described is place centrally of the flask or mold and the concrete oured about it. When .the concrete casting. as set and has been taken from the mold the cap andbottorn plug are removed from pipe 3,A

releasing `the sand and pipe 31 which 1s removed. Pipe Bremains inthe casting Rev v inforcing'material, as for example, wires 20, may be placed in the mold.

socket for the reception of pipe 3, formed by a low ange 24. Centeringr bolts, such as 25, (see 'Figure V3) may be` used to hold and center the cup relative to the flask. When thefflask is in castingposition and is filled with concrete, thebowl 23 is lled witha thick liquid grouting 26. Notches 27 in the lower edge of the flaskorvmold insure ree ressure communicating channels between t e cup 23 and the interior of the ilask. Spacing blocks 27 secure central placing of the upper end of the mold 1 in pressure chamber 5.

At as many points as may be .deemed necessary between the ends of the mold, pressure channels may be provided, through which pressure from without the mold may act upon the material within the mold. I have shown one such. This consists of a bracket-like or corbeled ilange 4 forming a cup or trough, which is in free communication with the interior of the llask through a slot or hole 40.

I prefer to provide a projecting rib 41 to form 'mits the introduction of a fluid un er pressure, as for instance, water, to the interior of the pressure chamber. A packing joint is used to secure ti htness. A pipe'61 passing through a pac 'ng joint in the head is connected to form an extension of the drain pipe 31. A coil 63 formed in this pipe rovides flexibility needed in applying an removing the head. Coil 63 can be disconnected from head by loosening packing joint 62 in head. A water drain cock 7 permits draining ofthe ressure chamber.

-In Figure 7 is shown a mold of quite different shape and superficial construction in which-the same principles are employed. In this, 7 represents the mold proper, that is, the shape-forming member, and 73 the body to be cast `in the mold. case a head 70 is provided with means,l as packing joint 62, whereby the under surface of the cap or plate may be connected with the water drainage pipe 63. The under surface of plate 70 is hollowed and receives the Vwater collecting drainage elements, such as fabric elements (wire or cloth) 72 and sand or other granular material 71.

In this The apparatus of Figure 8 is the same, ex-

cept that by vthe use of a' flexible and elastic figures represent the mold which is designed to be enclosed in a pressure chamber similar to 5 of Figure 1.

g In both Figures sent rinfrs of groutingthrough which pres' sure of the fluid in the pressure container is transmitted to the plastic concrete or cementitious compound from which the articles 73 and 81 are to be made. A mold of this type is placed in a pressure container and treated exactly as is the mold of Figure 1.

The operation of device such as shown and the method employed in pressure casting an article is as follows The mold is assembled as illustrated and placed in the pressure chamber, either before or after filling it with concrete. Grouting is placed in all openings, as cup 23, bracket or corbel 4, and at the upper end. In the latter place I would use a layer 21 of separating and sealing material, such, for instance, as greased paper or thin metal sheet, below the layer 22 of grouting.

7 and 8, 22 and 22repre- L I yThe mem er 8 is a base or form member for e t holding the resilient mold 80. These two The lower open end ofthe flask or'mold is placed in a cup or bowl 23, which may `have a 11d y 5 away from the concrete, also to replace thev shrinkage in the concrete casting due to compression. While I prefer to use grouting as described, this is not a real essential of the process.

The head 50 'is secured on the chamber 5 and Water pumped through the pipe 6 until the desired pressure is reached. Air is exhausted through cock 9. This pressure acts upon the plastic concrete to compress it. Surplus water flows to the composite central pgipe and is carried off through the pipe 6l.

ecause the pressure fluid entirely surrounds the flask or mold, there are no great unbalanced pressures acting thereon to strain it. It may therefore be made of relatively weak and cheap construction. The only part 'of the apparatus subjected toany material strain is the pressure chamber 5.

By employing the expedient of enclosing the entire `mold in a pressure chamber the mold is not subjected to a disruptive strain, which makes it possible to use forms of construction Which would be impossible if pressure was applied in the customary manner, that is, to the interior only of the `mold. Particularly is this advantage obvious in enabling the use of molds of relatively little strength and of cheap construction. This is due to the application of approximately the same pressure to the interior and exterior of the mold. The pressure used may be any the pressure chamber Will stand, as only the pres sure chamber is materially stressed thereby.

In any method of making pressure concrete, drainage of water forced from the concrete by the pressure applied thereto is essential. In this invention, such drainage is provided or in a special and very eiiicient manner by the pipe 31 and its associated parts.

What I claim as my invention is:

l. The method of molding concrete under pressure, which consists in applying pressure to the exterior of the mold at the same time pressure is applied to the concrete in the mold, and placing the concrete in the mold in communicationwith a lesser pressure.

2. The method of molding concrete under pressure which consists in placing the entire mold within a pressure chamber and applying pressure thereto to substantially equalize the pressures acting within and without the mold, a'ndf'aifording communication with the interior of the mold at atmosphericor other low pressure.

3. The method of molding concrete under pressure, which consists in applying pressure to the exterior of the mold at the same time pressure is applied to the concrete in the 'which will not unite with t mold, and at the same-time draining surplus water from the body concrete.

4. The method of molding concrete under pressure which consists in immersing the en tire mold within a body of water allowing communication between the water and the concrete Within the mold, and applying pressure thereto to substantially equalize the pressures actingwithin and withoutthe mold, meanwhile forcing and removing surplus water from within the body of concrete by the pressure thereon.

5. The method of molding concrete under pressure which consists in applying pressure directly to the concrete vin the mold, at distributed points thereof, and at the same time to the exterior of the mold, supplying surplus grouting externally of the concrete in the mold at such points, the pressure acting upon the concrete through such grouting, and placing the interior of the concrete mass in communication with a lesser pressure.

6. An apparatus for molding concrete under'pressure comprising a mold having o enings distributed thereover, whereby uid pressure exteriorly applied maybe more et?- fectively applied to the mass of the concrete in the mold, placing the concrete in the mold in communication with a lesser pressure, and means at such openings for retaining a bed of surplus grouting between the concrete in the mold and the pressure medium.

7. The method of molding concrete under pressure which consists in applying pressure to the concrete in the'mold, placing the interior of the concrete within the mold in communication with a lesser pressure, sup plyin surplus grouting at points which are direct y exposed to the pressure fluid and separating this surplus grouting from the body of the mold by a thin layer of material e concrete, to thereby provide a lane of cleavage.

8. An apparatus gol' molding concrete com prising a flask in which to mold the desired object, a pressure chamber adapted to receive therein the entire flask, the flask having o enings whereby the pressure within the chamer is im ressed upon the plastic mass within the asllr, and means communicating with the interior of the ilask to place the same under reduced pressure.

9. An apparatus for molding concrete objects comprising arnold, a pressure chamber adapted to receive the mold, means .for applying pressure to the interior of said pressure chamber, the mold having openings permitting application of pressure within the chamber to the mass within the mold, and a water drain-at lower pressure communicating with the interior of the mold.

10. An apparatus for molding concrete under pressure comprising a pressure chamber adapted to receive the concrete-forming mold, a removable head for said chamber,

Vso

' -means for introducing a uid under pressure to the interior of said chamber, the mold having openings for the communication to the mass therein o the pressure within the cham- 5 ber, and means embedded within the concrete in the mold for placing the same in communication with a lesser pressure.

Si ned at Seatle, King County, State of Was ington, this 8rd day of August, 1928. 1u WILLIAM M. MEACHAM.

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